Explosive actuated tool and method for driving a fastening stud or similar element



3,172,123 TRIVIN 4 Sheets-Sheet 1v 4 .f. 7., M a n n w u g .n MNM/M s 040 N 3 TMm n je mn n f mum sf 2 2 A... .l o SW y F t T W w F M".-` 6/6/ mv u 44 mln. E Y y v l Y, av uw H da W ,ac W64 M www# .a H

PLOSIVE ACTUATE 2 A FASTENING March 9, 1965 Filed oct. 3. 19e

lMarch 9, 1965 F. HELDER MAN ET AL 3,172,123 ExPEOsIvE ACTUATED TOOL AND METHOD FOR DRIVING A FASTENING STUD OR SIMILAR ELEMENT Filed oct'. s, 1962 IN VEN TORS N JAMAS nllwmuu/ e @72M f. M1612 J. F. HELDERMAN ETAL 3,172,123 ExPLosIvE AcIuATED Tool. AND METHOD Foa DRIVING A EAsTENING sIuD 0R SIMILAR ELEMENT I 4 Sheets-Sheet 3 o r Wwmfi e HH .7

s Mw up 7/// N NNN w www March 9, 1965 Filed oct. s, 1962 VDN March 9, 1965 J. F. HELDERMAN ETAL EXPLOSIVE ACTUATED TOOL. AND METHOD FOR DRIVINf? A FASTENING STUD OR SIMILAR ELEMENT 4 Sheets-Sheet 4 Filed- Oct. 3, 1962 QNN nitecl States Patent EXPLOSIVE ACTUA'EED TL AND MEIHD FR DRIVNG A FASTENING S'IUD 0R SEMILAR ELEMENT 'n .n

James F. Helderman, 2116 Ashley Road, Charlotte 8,

' NC., and WilliamHlHendersom lis., ChariottatLC.;

said `Henderson assigner to said Heiderman Filed st. 3, '1962, Ser. No. 228,080 Ztl Claims. (Cl. l-ii) The Vpresent invention relates to the driving of elements, .such as fastening studs, by an explosiveV actuated tool fin which an explosive charge is uniquely positioned for simplified firing of the charge to drive `a stud or other element, with the unique positioning and simplified firing of the charge permitting the tool to be simply and compactly constructed and yet be substantially safe from inadvertent tiring as well as from the hazards inherent in `tiring highv velocity type tools.

Briefly described, the explosive actuated tool of the present Ainvention comprises `a barrel member that has a bore in which an element to be driven by the tool is positioned prior to tiring, and has a chamber extending inwardly from the bore for receiving a percussion ignitible explosive charge. This chamber is shaped so that the explosive charge will be positioned-for ignition by an inwardly directed impact, `such as lproducedby an inward movement of an element in the bore.

For example, the chamber may be formed with a shoulder at the end of the bore for seating the rim of a blank cartridge with the body of the cartridge extending inwardly in the chamber and the firing surface facing outwardly at the shoulder, and the bore formed of a length slightly less than the length of a stud to be driven therefrom so that the tip .of the stud extendsY out of the bore; VWith this arrangement the tool is tired simply by striking the top-of the stud against the work piece into which the stud is to be driven, as byhitting the rear end of the-barrel member with a hammer as the tool is held in .place against thework piece, or by'impelling the Vbarrel member against the work piece from an initial position spaced therefrom. f Whenrthe tip of the stud strikes the work piece, the stud acts as the ring pin of the tool to transmit a force inwardlyV through the stud, causing an impact against the tiring surface of by utilizing a protective shield that is shitable between resulting explosion driving'the stud into the work piece.

This simplified tiring of the charge by an inward movement of the stud eliminates the need for any tiring mechanism as such, and permits the tool to be made in a simple and compact one-piece construction having only a stud bore and an explosive charge chamber, with the stud itself or means associated with the stud, such as a protuberance on the stud, efliciently serving as the firing pin of the tool.

Also, the firing by movement of the stud provides a positive means of tiring at the proper time and'minimizes inadvertent firing as there is no ring mechanism that can be accidentally triggered, and even inadvertent striking of the stud will not fire the tool unless it is a firm and strong blow. v

In addition, the initial positioning of the stud against the work piece eliminates the ricochet problem common to prior tools where the stud is fired from the rear of the bore and strikes the work piece at a high velocity.

The safety of the tool can be even further enhanced by utilizing a protective shield that is shiftable between a projected position in which it extends beyond the tip of the stud to protect against inadvertent striking of the stud and a retracted position at which the tip of the stud is exposed for striking. This shield may be formed with a lateral angeat its outer end for abutting a work ICC , a e piece to align the tool therewith `for proper driving of the element and to space the stud from the work piece when not properly aligned so that the tool will notl fire.

In a 'preferred embodiment of the present invention the above described barrel member with its stud bore and explosive charge chamber is incorporated in Va stud gun for sliding within an' outer barrel sleeve between a retracted cocked position and a projected firing position, with spring means for impelling the barrel vmember from cockedto firing position upon actuation of a trigger. With this embodiment the outer sleeve is positioned against a work piece andthe trigger actuated to permit the spring-to impel the barrel member, carrying a cart- "ridge and stud through the outer sleeve and against the work piece so that the tip of the stud strikes the work piece, with the stud acting as a firing pin to create an inwardly directed impact against the explosive charge for tiring the charge and driving the stud.

The stud driving forceofthe exploding charge may be controlled, after the driving ofthe stud is initiated, to reduce the recoil' force by incorporating ports in the barrel member communicatingwith the bore and spaced from theinner end of the bore. These Aports allow the expanding gas to escape, vas into an expansion chamber, and thereby substantially reduce the force available to cause recoil. The expansion chamber may be easily formed by 'an exterior recess in the barrel member covered by an outer sleeve, such as the outer barrel sleeve of the aforementioned stud gun embodiment.

The present invention also provides advantageous means for expelling spent charges, such as cartridges, which would normally 'be' difficult to lremove because of Vtheir position in the substantially*inaccessible exlplosive charge chamber inwardly of the bore, thus, an explosion chamber may be provided inwardly of and communicating with the explosive charge chamber and of a 'reduced cross-section so that upon firing of the charge the explosion enters the explosion chamber in back of the charge and as the explosion progresses it is directed forwardly and shaped by the explosion chamber to facilie tate expulsion of the spent charge.

Other and further features and advantages of the present invention will be apparent from the following description and'accompanying drawings, in which:

FIG. 1 is a vertical sectional view taken through an explosiveV actuated toolV according to one embodimen of the present invention; Y

FIG. 2 is a view similar to FIG. l showing the explosive actuated tool modified to include additional features of the present invention;

FIG. 3 is an enlarged vertical sectional view of a portion of an explosive actuated tool similar to FIG. 2;

FIG. 4 is a horizontal sectional view taken along line 4-4 of FIG. 2;

FIG. 5 is an enlarged vertical sectional View of the lower portion of an explosive actuated tool similar to the tool of FIG. 2 and incorporating yieldable detent means;

FIG. 6 is an enlarged elevational view of the threaded end of a fastening stud and a helical adapter coil for adapting the stud for use in an explosive actuated tool of the present invention;

FIG. 7 is an elevational view of a modified embodiment of a threaded fastening stud for use in the present invent-ion;

FIG. 8 is an elevational view of a threaded fastening stud with an extender shank extending therefrom to adapt the stud to a particular bore length of an explosive actuated tool; v

FIG. 9 is an enlarged elevational view of an extender or spacer plug for insertion in the bor-e of an explosive actuated tool to adapt a `fastening stud to the length of the vbore of the tool; Y

FIG. is a side elevational view, partially in section, of a stud gun embodying the present invention, and showing the element-s in cocked position prior to firing;

FIG. 11 is a vertical sectional View of .thepstud gun of FIG. 10 showing the elements in firing position;

FIG. 12 is an end elevational view of the protective shield of the stud gun of FIG. 10 as viewed from the right of FIG. 10;

FIG. 13 is a side elevational View, partially in section, of a modified embodiment of the stud gun of FIGS. 10 and l1; and

FIG. 14 is a vertical sectional view of the muzzle end of a further modiiication of the stud gun of FIGS. 10 and 11.

In the embodiment illustrated in FIG. 1, the explosive actuated tool of the present invention comprises simply a cylindrical barrel member formed with a bore 22 extending inwardly from the muzzle 24 of the .tool and with a chamber 26 extending inwardly from and communicating with the bore 22 from an inner shoulder 28 at the inner end of the bore 22, with the chamber 26 being of a smaller diameter than the bore 22 as reduced by the shoulder 28. The bore 22 is provided for positioning therein of a fastening stud 36 or other element to be driven by .the tool, and the charnber 26 is provided for receipt of an explosive charge, such as a blank cartridge 30, with the inner shoulder 28 providing a seat for the rim 32 of the cartridge 30 for positioning of the firing surface 34 facing outwardly and the body of the cartridge extending within .the chamber 26.

The stud 36 is provided with a firing pin protuberance 38 extending from the `head 40 of the stud for contact with the tiring surface 34 of the cartridge 30, with the head 40 -being of a diameter only slightly less than the diameter of the bore 22 so that upon firing of the cartridge the head 40 will serve as a piston to drive the stud 36 from the bore 22. The tip 42 or outer end of the stud 36 is pointed for driving into a work piece, such as a concrete iioor or wall or any other type of material or structure.

The stud 36 is of an overall length slightly greater than the length of .the bore 22 so that when the cartridge 30 and the stud 36 are positioned in the barrel meinber 20 the tip 42 of the stud will extend slightly beyond the muzzle 24 of the barrel member. In this manner the tool is actuated simply by striking the extending tip 42 of the stud 36, which transmits the impact to the tiring pin -protuberance 38 and against the tiring surface 34 of the cartridge 30, to ignite the cartridge by percussion with the pursuant explosion driving the stud 36 into the work piece.

This tiring by striking the tip 42 of the stud 36 against the work piece can be .accomplished in any desired manner as by rst placing the tool against the work piece and then striking the end of the tool with a hammer, or by striking the entire barrel member unit 20 `against the work piece, which can be facilitated by forming a hammer handle on the barrel member 20.

In most -instances it is desirable to provide some means of aligning the stud 36 in the bore22 for straight driving of the 4stud into the work piece. This can be accomplished as illustrated in FIG. 1 by aiiixing a guide washer 44 adjacent the tip 42 of the stud 36. This guide washer 44 is slidable on the stud 36 and is initially positioned by a friction fit. This washer 44 serves as a laterally extending iiange of a diameter slightly ,less than the diameter of the adjacent bore portion, thereby centering the tip 42 of the stud 36 within the bore. When the stud 36 is driven, it slides through the washer 44, which remains against the work piece as a Washer vfor the head 40 of the stud.

As illustrated in FIG. l, the muzzle end 48 of the bore 22 is slightly enlarged and the diameter of the guide washer 44 is slightly less than the diameter of this enlarged muzzle end 48 of the bore 22, this enlargement will permit the incorporation of a yieldable detent to initially engage the washer 44 and hold the stud in the bore 22 prior to tiring, but without extending into the path of the head 40 of the stud 36. Such a yieldable detent is shown in FIGS. 5, 10, 11, 13 and 14, and will be described in detail below.

As the cartridge chamber 26 is relatively inaccessible, opening only at the iniier end of the bore 27, it would be diiicult to remove a spent cartridge that has become lodged in the chamber 26. To facilitate expulsion of spent cartridges, an explosion chamber S0 is provided inwardly of and communicating with the cartridge chamber 26. This explosion chamber 50 tapers at the Juncture 52 with the cartridge chamber 26 to a substantially reduced cross-section so that upon firing of the cartridge 3) the 'force of the explosion will expand into the explosion chamber 50 and be shaped by the reduced cross section to collapse the cartridge 30 and expel it from the chamber 26 for ready removal from the bore 22.

From the above description it is apparent that the embodiment illustrated in FIG. 1 is a simple and compact construction requiring no movable parts, such as a firing mechanism, and can be made of a one-piece constructhe stud is not in place against a work piece.

A modification of the embodiment of FIG. 1 is illustrated in the tool of FIG. 2, which is similar to the tool of FIG. 1 in that it has a cylindrical barrel member S4 having a bore 56 for positioning of a stud 58 therein, for a cartridge chamber 60 defined by an inner shoulder 62 for positioning of a cartridge 64 for iiring by a protuberance 66 of the bead 68 of the stud 58 upon striking of the tip 70 of the stud against a work piece. This embodiment also includes an explosion chamber 72 extending inwardly from the cartridge chamber 60.

In addition to the above elements similar to the ei'ribodid ment of FIG. 1, the embodiment of FIG. 2 includes an expansion feature for allowing the explosive force to dissipate and thereby reduce recoil. This is' accomplished by arranging ports 82 in the barrel member 54 communieating between the bore 56 and an expansion chamber 74, which 4is formed by ari exterior recess 66 in the surface 78 of the barrel member 54 and an outer cylin-l drical sleeve 8d) positioned over the barrel member 54 completely covering exterior lrecess 76. There are four" symmetrically arranged ports 82, and they are spaced from the inner end of the bore 56 so that upon explosion` of the cartridge 64 the explosive charge drives the head of ythe stud without expansion of the force until the head of the stud passes the ports 82 to expose the ports and permit the explosive force to expand through the ports 82 into the expansion chamber 74.

The cylindrical sleeve of this embodiment is positioned on the barrel member 54 with O-rings that not only position the sleeve 80 but also seal the expansion chamber 74 and are formed of resilient material, such as rubber, to minimize vibrations and sound resulting from the explosion, and particularly the expansion of the explosive force into the expansion chamber 74. To insure retention of the sleeve 80 `in proper position on lthe tool even during recoil, the barrel member 54 is provided with la slightly enlarged muzzle end 84 so that upon recoil of the tool the muzzle end 84 will prevent the sleeve 80 from sliding forwardly on the barrel member 54.

It will be noted that the stud 58 in the embodiment ofI FIG. 2 differs from the stud 36 of the embodiment of FIG. 1 in that the heads 68 of the stud 58 of FIG. 2 is threaded. These threads would normally permit at least part of the explosive force to escape without the full force of the explosion being directed to driving the stud.-

:savanne To compensate for this, a driver cap Sdis positioned. over the head 68 and is provided with a slot S8 to permit extension of theY tiring pin protuberance 66 ofthe` stud 53; This driverl cap has' a cylindricalwall 901ofa diameter slightly less-than- :the diameter o-f the boreS so that'itaotsrasa piston to drivethe stud upon explosion ofth'ecartridge 64:

An `alternate form of a closure for-thevthreaded head., erof the stud'SS is-illustrated in the enlargementof.

a threaded -stud is illustrated irrFlG. 7, wherein the stud. 94^hasa' threaded head* @diend is providedrwith a later` ally'extendingeilange 9,8Yat the base ofithehead of a diam-eter slightly lessthan-thefdiameteri of t-heWbore in which the studfis to be positioned, therebysubstantially sealingthehead l-for drivingasfa pistonzby the explosion off the charge within thetool.

As rmentioned`l previously, Ithelength` of the stud 36: of the embodiment of FIG 1 is slightly. longer than the length of the bore-22 ofi-the` barrel member Zilsothat the tip 42of the -stndextends slight-lybeyonds'the muzzle Zit-'for firing v eng-agementof` the VworkV piece. However, it is notfnecessary to.useastandardflength stud, as.it is often' desirablefor-ap-anticulan purpose tousezashorter stud. To accommodate such shorter studs, extender means-may bevulscdfwithlthe studsA so theta single-:tool can-betised4 for many stud length applications; Such extender means are sho-Wn in FIGS. 8 and, 9j in'FIG. S the stud. 1l3-hfaslan extender shank V1&2 .extending from the head 11M- of; the studi and .separated therefromxby areduced di'ameterf portion 1116. so that. after driving Vthe studilitheextenderrshank ltlZ'can be broken oii at lthereduced diameterV por-tion11il6. Thez extender shank 102 is pro-vided with.l a piston` rim 163 anda iiringpinV protuberance. 1101 similar-1 to `the corresponding elements of-fthe previously` described studs.

The extender means illust-rated, in FIG. 9-is a solid cylindrical plug 112 Vhaving a'iiring pin protuberance 114 extending; fromV onel end 116-tl1ereof- This plug 112 is intendedto lbe-inserted--in thebore loft-he tool after positioning of theV cartridge and before positioning-of the stud' and is of a length- Vsufticientto combine with Vthe length of the stud to posit-ionthe tip of the stud out- Y' wardly oft-he muzzle of the barrel member-so that the tip of the stud carrbe struck and-.the impa-'ott-ranslmitted through the plugV to tire thel cartridge. Representative plug lengths are indicated'in dot-dash lines in FIG. 9.

v As a stud isloadedinto the tool throughnhe muzzle and the tool is red .byplacing the muzzle against a work piece, it is- .apparent that the tool must be moved from a loading position to a tir-ing position and in so doingl it may be difficult to retainA the stud in the tool. Accordingly, a tool `ofthe present-invention may be provided with the aforementioned detent means. Such? detent-:means are illustrated clearlyV in the enlargement-of FIG. 5, which shows the muzzle `end 84 of the barrel member-54 ofthe embodiment of FIG. 2. These detent means 118consis-t of a ball detent- 120- partially prot-ruding through .an opening-122in the enlarged muzzle end of the bore 56. The opening 122 is of a diameter less than the diameter ofthe ball' so that the ball cannot completely pass therethrough.y The ball is lheld in a yieldable protruding positionrby a` spring 124'rcompressed within aoohannel 126- extendingwlaterally from the opening 122 tothe outer surface-of the barrel member 54 and held rtherein by a threaded plug123. Thuis the ball detent120 yields to permitthe guide washer 44 on the stud 58 to pass therebeyond into the bore 56 and retains the stud byfengagernentiw-ith the guide washer to prevent the stud fromiallingfoutsofrhe bore until theV cartridge isred, at whichY time the force of the explosion willv cause the :washer to engage andfretract the ball,`

detent 120,. permittingthe,v washer` and-studV 581e p ass thereby.

Thepresent invention may be advantageously incorporated in a stud gun constructionfsuch as thatillustrated in FIGS; 10-14. In thisternbodiment the stud gunr130 hast anA outer barrell sleeve, 1321. within which Van inner barrel member 13iis slidable between a, retractedY or cocked position as;shown.in.FIG. 10 and aprojected or 'ringpositionasshown in BIG. 11. Y

The inner barrel member 134 is preferably of a construction .substantially the samefas the cylindrical barrel member 2i?. ofthe embodiment-of FIG. 1 or'the cylindrical barrelmemberv 5@ of the embodiment of FIG. 2. Thus this .inner barrel memberlgis provided with a stud bore.' 136g afcartridgechamber, 13.8; extending inwardly from the stud. bore 136and deiined. at its outer end` by a Y shoulder L41),.anden explosionchamber 14,2,v extending inwardl-yirorn andatareduced diameter with respect to the cartridge chamber 1.33; Theinner barrel memberl 134 is also similarlyprovidedwith detentmeanslll. at the muzzle end1l45 thereof for retaining a stud liin the stud bore y13.6. An expansionchamber 151),` serving the same. purpose as the expansion chamber 74 of the embodiment of. FVIGrZ: is defined by an exterior, recess152 in the outer surface of theI inner barrel member 134 and the outer barrel sleeve 132.. This Yexpansion chamber communicateswith, the interior of the stud bore 136by means offour equallyspaced ports 151positioned similar to the ports82xof the` embodimenti ofFIG. 2.

Theinner barrel member'.V 134, is impelledfromits retraeted. cocked positiony (ElG. 1G.) toits'projected ring position (FIG. 11) by `a coilspring 15e that has rone end 158 seatedy inthe endletlof the outer; barrel sleeve 132 andritszother endletbiasedagainst the inner'barrel member- 134; 'Vl/hen the inner barrel member.y 13.4 is in its cocked or retracted position, the spring LSais compressed. Ai second springlef is` positioned within the first spring 156, and isA similarly mountedto bias the. inner barrel member forwardly. 'Howeven as seen iniFIG. 11, this y second spring 164 is substantially shorter than the iirst spring landdoesnot remain in contact with the inner barrel member 13d-throughout the entire firing stroke thereof, but does serve to add to the initial impelling force and to add to the spring means. available to absorb the recoil ofthe inner barrel member 134Yafter firing. To further reduce' the eiectof recoil, a third spring 166 is mounted within the-second spring'164, but extending only a relatively short distance from the end 150 ofthe outer barrel sleeve 132i Thistin'rd spring 166 is relatively stili and is; provided,- for stopping the rearward movement of theinnerbarrel member 13dl onrecoil thereof.`

The inner barrel member 134 is retained in its cocked or retracted position by means Vof a trigger mechanism 168 comprising arpivoted trigger element 176 having a trigger Y out of the latching recess 17o of the inner barrel member. 134, which releases the inner barrel member to be im` pelled-forwardly-by the springs 156 and 164. When the inner barrel member 134 reaches its projected or ring position, the extending end of the stud 148 will strike the work piece against-which the outer barrel sleeve 132 is .positioned prior to firing, therebytransmitting an inwardly directed impact against the cartridge 184, which impact fires the cartridge to drive the stud by the resulting explosion into the work piece. The repercussion from the explosion drives the inner barrel member 134 backwardly against the springs 156, 164 and 166, which absorb this recoil and return the inner barrel member 134 to its projected position for reloading.

The inner barrel member 134 is provided with a hand lever 186 that extends through a slot 188 in the outer barrel sleeve 132 for engagement by the operator to retract the inner barrel member 134 to its cocked position against the urging of the springs 156 and 164 after reloadmg.

Although the stud gun 130 of the embodiments of FIGS. through 14 includes a trigger mechanism 168, this trigger mechanism does not itself tire the cartridge 184. If the trigger is accidentally actuated, the inner barrel member 134 will be impelled to its firing position but the cartridge will be fired only if there is a work piece or other object against which the tip of the stud 148 can strike. If there is no object at the muzzle end of the gun the cartridge will not fire. Thus the present invention incorporates `a very significant safety feature.

A further safeguard, as well as beneficial means for positioning and aligning the stud gun 130, are provided by a tubular protective shield 198 that is shiftably mounted at the muzzle end 192 of the outer barrel sleeve 132. This protective shield 198 has a laterally extending outer flange 194 and is shiftable from a projected position at which the outer llange 194 is spaced from the muzzle end 192 of the outer barrel sleeve 132 and an inner retracted position at which the outer flange 194 abuts the muzzle end 192 of the outer barrel sleeve 132. This tubular protective shield 190 has lan inner diameter slightly greater than the outer diameter of the outer barrel sleeve 132 so that a coil spring can be mounted therebetween. This coil spring 196 is biased between a collar 198 secured to the exterior of the outer barrel sleeve 132 inwardly of the muzzle end 192 thereof and the inner surface 200 of the outer flange 194 of the shield 198, Thus this spring 196 normally urges the protective shield 190 to its projected position as seen in FIG. l0. The shield 190 is prevented from moving off of the outer barrel sleeve 132 by an inturned ridge 202 of lesser diameter than the diameter of the collar 198 so that the ridge 202 will engage the collar 198 and prevent the shield 190 from passing therebeyond. However, the shield 190 is provided with a plurality of longitudinal slots 284 that permit it to expand and allow the ridge 202 to pass over the collar 198 for removal of the shield 190 by a force greater than that of the spring 196.

The outer flange 194 of the tubular shield 190 has a central opening 206 of a diameter less than the major diameter of the inner barrel member 134, and t-he muzzle end 146 of the inner barrel member 134 is provided with an annular recess 208 that permits the unrecessed portion of the end of the inner barrel member 134 to extend through the central opening 206 of the outer flange 194 of the shield 190 and be positioned flush therewith for firing while the recessed portion abuts the inner surface 200 of the shield flange 194.

In use the protective tubulal` shield 190 is normally positioned cin its projected position by the spring 196, thereby preventing objects from being close enough to the muzzle end 192 of the outer barrel sleeve 132 to be struck by the end of the stud should the trigger mechanism 168 be accidentally actuated, thus preventing inadvertent firing lof the tool. When it is desired to drive a stud with this stud gun 130 the outer flange 194 of the shield 190 is placed against the work piece and the -handle 180 is forced forwardly to force the outer barrel sleeve 132 into the shield 190 for retraction of the shield with respect to the sleeve so that when the inner barrel member 134 is impelled by the spring 156 upon actuation of the trigger mechanism 168 to its firing position the end of the stud 148 will strike the work piece and fire 8 the cartridge 184 to drive the stud 148 into the work rece.

p The outer flange 194 of the shield 190 serves as a positioning and aligning element that automatically positions the gun for proper firing simply by placing the flange 194 flush against the work piece. If the flange is not flush against the work piece, but is tilted with respect thereto, the resulting tilting will cause the muzzle end 146 of the inner barrel member 134 to be spaced from the work piece when in firing position yso that the stud 148 will not strike the work piece and the cartridge 184 will not be fired.

In some instances the material into which it is desired to drive the stud will not be hard enough to pnoduce a ring impact when the stud strikes the object. Thus when it is desired to drive a stud into soft wood the stud tip will penetrate the wood rather than moving inwardly in the barrel, with the result that the stud will not fire the cartridge. To provide for firing of studs intro soft material, the stud gun of the present embodiment provides a circular recess 218 surrounding the central opening 286 of the outer ilange 194 of the protective shield 198, for mounting of a firing disc 212 of metal or other hard material across the opening to provide a striking surface for the end of the stud when the lstud is to be fired into soft material. The mounting shoulder 214 formed Iby the circular recess 210 for mounting of the firing disc 212 may be diametrically split as at 216 and the ihalves oppositely magnetized so that a metallic disc will be retained in the recess prior to placing of the stud gun against a work piece. The `above described protective shield is clearly illustrated in FIGS. l0, ll, 12 and 14, with FIG. 14 also showing the firing disc 212.

As illustrated in FIGS. 13 and 14, the stud gun 130 of this embodiment can be modified to drive studs of various lengths by using alternate inner barrel member constructions. However, the stud length adapter of FIGS. 8 and 9 could also be used in this embodiment.

In FIG. 13 the inner barrel member 218 is formed with an interchangeable muzzle portion 220, a tubular oonnecting portion 222, and a rear base portion 224. The rear base portion 224 is constructed similar to the inner barrel member 134 of FIG. 10 rearwardly of the ports 154 and has its similar elements numbered the same as in FIG. 10. In addition, longitudinally spaced threaded recesses 226 are formed in the outer surface of the rear base portion 224 for receipt of the set screw 228 used to position the tubular connecting portion 222 in an adjusted length position winh respect to the rear base portion 224. T-he tubular connecting portion 222 is also connected by a set screw 230 to the muzzle portion 220, which is lof a selected length and is interchangeable with similar muzzle portions of different lengths to accommodate different length studs. The muzzle portion 220 Ihas a recessed surface 232 for dening an expansion chamber in combination with the interior of the tubular connecting portion 222. Ports 234 communicate between this expansion chamber and the bore of the barrel member 218. The recessed surface 232 terminates rearwardly in a flange 236 that abuts the rear base portion 224 to firmly position the portions in place.

In the modified lbarrel construction of FIG. 14, the barrel member 238 is formed with a rear base portion 240 substantially identical to the rear base portion 222 of the barrel member 218 of FIG. 13, having similar threaded recesses 242 for adjustable positioning of a forward muzzle portion 244 by means of a set screw 246. The muzzle portion 244 extends from the rear base p0rtion 240 to the muzzle of the barrel member 238, and is hollow for a substantial length from the inner end thereof. An interchangeable tubular member' 248 is seated in the hollow area of the muzzle portion 244, and has tapered ends 250 that seat in complementary tapered surfaces 252 of the muzzle portion 244 and rear bore 9, portion 240 to mate rmly with these portions and combine therewith to `form a' continuous bore 2'54. This tubular member 248 is provided with ports 2567fo1" communication between the bore'2'54 and the space within the muzzle portion 244 outwardly of the tubular inember 248, which space forms an expansion chamber. To accommodate studs of different length, diierent length tubular members 248 are interchangeable with the muzzle portion 244 accommodating'the change by selective positioning with respect to the vthreaded recesses V242 of the rear baseV portion 240.

The present invention has been 'described in detail above for purposes of illustration only and is not intended to be limited by this description orotherwise except as deiined inthe appended claims.

We claim:

1. An explosive actuated tool for' driving an element, such as a fastening stud, 'by an explosive charge, said tool comprising a barrel member having a bore-for positioning vtherein of an element to be driven by said tool 4and a chamber communicating with said bore inwardly of the position of said element for receipt of Aa percussion ignitible explosive eharge, said chamber being shaped forpositioning said chargefor ignition by an inwardly directed impact producible by an inward relative movement of an element in said bore.

2. An explosiveactuated tool according to"cl`aim l and characterized further in that the length of said bore outwardly of said chamber is such that an element positioned therein will extend outwardly of the barrel member for striking against an object, such as a workpiece into which said element is to be driven, to produce said inwardly directed impact.

3. An explosive actuated tool according to claim 1 and characterized further in that said barrel member has an explosion chamber communicating with the explosive charge receiving chamber inwardly of the position of the charge for directing the explosion to facilitate expulsion of the spent charge from said bore upon tiring.

4. An explosive actuated tool according to claim 1 and characterized further in that said barrel member has an expansion chamber spaced laterally from said bore with ports connecting said bore and expansion chamber intermediate the ends of the bore for expansion of the explosion into the expansion chamber after the element to be driven has been driven past said ports.

5. An'explosive actuated tool according to claim 4 and characterized further in that said expansion chamber is formed by an exterior recess in said barrel member and a sleeve member covering said recess.

6. An explosive actuated tool according to claim 2 and characterized further in that a protective shield is mounted on said barrel member and is shiftable between a projected position in which it extends beyond the outward extension of an element positioned in the bore of the barrel member to protect against unintentional tiring of the tool and a retracted position exposing said extending end of the element for tiring.

7, An explosive actuated tool according to claim 6 and characterized further in that said protective shield has a laterally extending ange for abutting a workpiece to align the tool prior to drivingof the element.

S. An explosive actuated tool according to claim 6 and characterized further in that said protective shield is provided with a recess surrounding the end of said bore, and a tiring disc is seatable in said recess across said bore for firing engagement with the end of the element when the protective shield is in retracted position.

9. An explosive actuated tool for driving an element, such as a fastening stud, by an explosive charge, said tool comprising a barrel member having a muzzle and a bore extending from said muzzle to an inner shoulder for positioning in the bore of an element to be driven by said tool, said barrel member having a cartridge chamber extending inwardly from said inner shoulder for positioning of an explosive `cartridge in said chamber with the rim of the cartridge seated against said inner shoulder for iiring of the ycartridge by an Vinwardly directed impact producible by 'aninward relative movement of an element in said bore. j v

10'. Anexplosiveactuated tool according to claim 9 and characterized `further in that said :barrel member has an explosion'chamber communicating withand extending inwardly from said cartridge chamber at a reduced crosssection for'directing the explosion'to facilitate expulsion of the spent cartridge from said bore upon tiring.y

l1l. Anexplosive actuated tool for driving an element, said tool comprising a barrel member having a muzzle and a bore extending from said muzzle `to an Vinner shoulder and a cartridge chamber extending inwardly fromrsaid 'inner shoulder, an explosive cartridge-having a rimmed iiringend, said cartridge being lpositioned in said cartridge chamber withthe rim ofthe ring end seated against said shoulder and said iiring'end 4facing outwardly for ring 'by fan inwardly directed impact, aiiring pin element posi- -tioned in said `bore outwardly ofsaidfcartridge having an .Y

'inner end in Contact 'wit-li saidiiring end of said cartridge and an outer end extending beyond said muzzle for striking against an objeet Vinto which said element is to be dr-ivento impart through said element a ring impact to said cartridge.

12. An lexplosive actuated tool for driving-anelement according to claim l1 and characterized further in that said element inner end has a-protuberance integral with and extending inwardly from said element inner end for contact with said firing end of said cartridge.

13. An explosive actuated tool for driving an element, said tool comprising a barrel member having a bore and a chamber extending inwardly of said bore,'an explosive charge positioned in said chamber for firing by an impact directed inwardly through said bore, a iiring pin element positioned in said bore movable inwardly to produce a tiring impact to explode said charge, said bore having an enlarged muzzle-end, a ange member-associated with said element in said enlarged muzzle end of said bore, and yieldable detent means in said barrel member at said enlarged muzzle end of the bore yieldably engageable with said flange member to retain said element in said bore prior to tiring of said tool. v

14. stud gun for driving a fastening stnd or the like comprising an outer barrel sleeve having a muzzle end, an inner slidable barrel `in said outer barrel sleeve and slidable therein between a retracted position and a ring position at said muzzle end of the outer barrel sleeve, said lnner slidable barrel having a bore for positioning therein of a stud or the like to be driven by said gun andV a chamber extending inwardly from said bore for receipt of'an explosive charge ignitible when said inner barrel is in firing position to drive said stud, means operable to impel said inner slidable barrel from retracted to tiring pos1t1on.

15. A stud gun according to claim 14 and characterized further in that said inner slidable barrel has ports extending laterally from said bore and an exterior recess communicating with said ports and forming with said outer barrel sleeve an expansion chamber foriexpansion of the explosion within the bore.

16. A stud gun for driving a fastening stud or the like comprising an outer barrel sleeve having a muzzle end, an inner slidable barrel in said outer barrel sleeve and slidable therein between a cocked position within said outer barrel sleeve and a tiring position at said muzzle end of the outer barrel sleeve, said inner slidable barrel having a bore for positioning therein of a stud or the like to be driven by said gun and a chamber extending inwardly from said bore for receipt of an explosive charge ignitible to drive said stud when the inner slidable barrel is in firing position, resilient means for impelling said inner slidable barrel from cocked to tiring position and for absorbing the recoil of the inner slidable barrel upon firing, trigger means for retaining said inner slidable barrel in cocked position against the urging of said resilient means and operable to release said inner slidable barrel for impelling to firing position by said resilient means.

17. A stud gun according to claim 16 and characterized further in that an explosive charge is positioned in said chamber for ignition by an impact directed inwardly of said inner slidable barrel and a stud is positioned in said bore for extension outwardly of the inner slidable member for striking a work piece upon sliding of the inner slidable member to firing position, said stud having an inner tiring pin end for tiring said charge to drive the stud into the work piece when the stud strikes the work piece.

18. A stud gun according to claim 17 and characterized further in that a protective shield is shiftably mounted on said outer barrel sleeve and is shiftable between a projected position outwardly of the muzzle of said outer barrel sleeve beyond the position of the stud when the inner slidable barrel is in firing position and thereby protecting against inadvertent firing, and a retracted position substantially ush with the muzzle of said outer barrel sleeve, and means for releasably positioning said protective shield in projected position.

19. A method of driving a stud or similar element by an explosive charge comprising loading a cartridge in the bore of a barrel member with the firing surface thereof facing outwardly of the bore, positioning a stud in the bore with an end extending outwardly beyond the barrel member, striking the extending end of the stud against a work piece to cause the stud to move inwardly to produce an impact against said cartridge to ignite the cartridge with the resulting explosion driving the stud into the work piece.

20.' A method of driving a stud or similar element by an explosive charge comprising loading a cartridge in the bore of a barrel member with the firing surface thereof facing outwardly of the bore, positioning a stud in the bore outwardly of said cartridge with an end facing outwardly, striking said end of the stud against a Work piece to cause the stud to move inwardly to produce an impact against said cartridge to ignite the cartridge with the resulting explosion driving the stud into the work piece.

References Cited by the Examiner UNITED STATES PATENTS 2,166,041 7/39 COX l-44.5 2,533,851 12/50 Temple l--44.5 2,637,241 5/53 Webber 85-10 2,761,348 9/56 Williams et al 85-l0 2,804,620 9/75 Gannon 1-44.5 3,112,487 12/63 Hilti 1-44.5

GRANVILLE Y. CUSTER, 111 Primary Examiner. 

19. A METHOD OF DRIVING A STUD OR SIMILAR ELEMENT BY AN EXPLOSIVE CHARGE COMPRISING LOADING A CARTRIDE IN THE BORE OF A BARREL MEMBER WITH THE FIRING SURFACE THEREOF FACING OUTWARDLY OF THE BORE, POSITIONING A STUD IN THE BORE WITH AN END EXTENDING OUTWARDLY BEYOND THE BARREL MEMBER, STRIKING THE EXTENDING END OF THE STUD AGAINST A WORK PIECE TO CAUSE THE STUD TO MOVE INWARDLY TO PRODUCE AN IMPACT AGAINST SAID CARTRIDGE TO IGNITE THE CARTRIDGE WITH THE RESULTING EXPLOSION DRIVING THE STUD INTO THE WORK PIECE. 